Process for metallating nonconjugated diene-containing ethylene polymers and graft polymers prepared therefrom

ABSTRACT

A process is provided for metallating ethylene polymers which have polymerized therein a minor amount of nonconjugated diene. Metallation is accomplished with a blend of three metallating reagents: (a) an alkyllithium compound; (b) a potassium alkoxide; and (c) a chelating tertiary diamine. The metallated polymers so prepared may be reacted with one or more anionically polymerizable monomers to form graft polymers or with a reagent such as carbon dioxide to form a functionalized polymer. When the anionically polymerizable monomer has two or more polymerizable sites, the metallated polymer is reacted with a modifying compound such as alpha-methylstyrene before it is reacted with the monomer(s). Certain of the graft polymers behave as thermoplastic elastomers whereas others are thermoplastic. The blend of metallating reagents may be used with any polymer having partial or complete unsaturation.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional of application Ser. No. 899,183, filed Aug. 18,1986, now U.S. Pat. No. 4,761,456, which is a a continuation-in-part ofApplication Ser. No. 745,763, filed June 16, 1985, now abandoned.

BACKGROUND OF THE INVENTION

The present invention relates generally to metallating ethylene polymerswhich have polymerized therein a minor amount of at least onenonconjugated diene. More specifically, the present invention relates toan improved process for metallating such polymers with a three-componentmetallation system. The present invention also relates to graft polymersand functionalized polymers prepared from the metallated polymers.

The term "metallation", used in its broadest sense, describes asubstitution reaction in which a non-carbon atom is replaced by analkali metal atom. In a narrower sense, it is believed that metallationof unsaturated polymers occurs by allyl hydrogen exchange whereby ananion is produced. The resulting anion is stabilized by declocalizationwith the adjacent double bond. The alkali metal atom is suitablyprovided by an organo-alkali metal compound.

Metallation of conjugated diene polymers with an organolithium compound,e.g., n-butyllithium, in combination with either a potassium alkoxidee.g., potassium-tert-butoxide or potassium-tert-amyloxide, or a tertiarydiamine, e.g., tetramethylethylenediamine (hereinafter "TMEDA"), isknown. See, A. F. Halasa et al., "Metallation of Unsaturated Polymers byUsing Activated Organolithium Compounds and the Formation of GraftPolymers II", Journal of Polymer Science, Volume 14, pages 497-506(1976). Halasa et al. note that each combination has one or moresignificant drawbacks. The n-butyllithium/TMEDA combination, whilegenerally efficient for metallation of conjugated diene polymers such aspolybutadiene, promotes polymer chain scission or degradation wherethere is a double bond in the polymer backbone. Then-butyllithium/potassium-tert-butoxide combination, when compared withthe n-butyllithium/TMEDA combination, alleviates some of the chainscission problem but at a cost of lower metallation efficiency.

E. W. Duck et al., in U.S. Pat. No. 3,703,566, disclose metallation ofunsaturated hydrocarbon elastomers and formation of graft copolymers bypolymerizing one or more monomers in the presence of the metallatedelastomer. The elastomer, more commonly known as an "EPDM terpolymer",has polymerized therein ethylene, a 1-olefin such as propylene and anonconjugated diene monomer. Metallation is accomplished by admixing asolution of the terpolymer in an inert organic solvent with a complex ofa saturated alkali metal hydrocarbon and a polar compound. The alkalimetal hydrocarbon may be an alkyllithium compound such asn-butyllithium. The polar compound may be a tertiary diamine, such astetramethylethylenediamine, or an alkali metal alkoxide, such aspotassium-tert-butoxide. In other words, Duck et al., like Halasa etal., use a two-component metallation composition.

Polymer chain scission and low metallation efficiency are bothundesirable. Polymer chain scission, or breaking up the polymerbackbone, generally results in reduction of desirable polymerproperties. Low metallation efficiency means excess metallatingcomponents may be present upon completion of metallation. Excessmetallating components compete with the metallated ethylene polymer forreagents added subsequent to metallation. This competition provides amixture of products rather than a generally pure product. Free alkalimetal atoms (those not bound to the ethylene polymer) usually must beneutralized before use of the metallated polymer. The neutralized alkalimetal atoms may adversely affect final product properties. Alkyllithiumand potassium alkoxide compounds are also expensive. As such, finalproduct cost escalates with increasing amounts of one or more of thesecompounds.

A metallating composition which provides enhanced metallation efficiencywould be desirable. A metallated polymer with enough alkali metal sitesto promote adequate functionalization or grafting of the polymer andthereby yield a useful polymer product would also be desirable. Ametallated ethylene polymer suitable for use in preparing athermoplastic elastomer would further be desirable. Graft polymershaving either themoplastic or thermoplastic elastomer properties wouldsimilarly be desirable.

SUMMARY OF THE INVENTION

In one aspect, the present invention is a process for metallating anethylene interpolymer, said interpolymer having polymerized thereinethylene, a nonconjugated diene and at least one 1-olefin having threeor more carbon atoms, the process comprising: (a) providing an admixtureof the ethylene interpolymer and a saturated nonpolar hydrocarbonsolvent; (b) forming an intermixture of the admixture and activatingamounts of a tertiary diamine and a potassium alkoxide; and (c)contacting the intermixture with an amount of at least one lithium akylcompound under conditions sufficient to provide more than about twentypercent of the polymer molecules with at least one lithiated site, theamounts of the tertiary amine, the potassium alkoxide and the lithiumalkyl also being sufficient to provide a degree of metallation greaterthan the degree of metallation attained with (1) the potassium alkoxideand the lithium alkyl compound, or (2) the tertiary amine and thelithium alkyl compound, or by adding the degrees of metallation attainedwith (1) and (2). The lithiated ethylene polymer is a reactionintermediate which may be functionalized by reaction with suitablereagents or used as an anionic polymerization initiator. If desired, thelithium alkyl compound may be added before the tertiary amine and thepotassium alkoxide without adverse effects.

In a second aspect, the present invention is a process for preparing agraft polymer having an ethylene polymer backbone and a plurality ofside chains, the process comprising: (a) metallating an ethylenepolymer, said polymer having polymerized therein ethylene, anonconjugated diene and at least one 1-olefin having three or morecarbon atoms by a process which comprises: (1) providing an admixture ofthe ethylene polymer and a saturated, nonpolar, hydrocarbon solvent, (2)forming an intermixture of the admixture and activating amounts of atertiary amine and a potassium alkoxide, and (3) contacting theintermixture with an amount of at least one lithium alkyl compound underconditions sufficient to provide more than about twenty percent of thepolymer molecules with at least one lithiated site; and (b) contactingthe metallated ethylene polymer with a reagent selected from the groupconsisting of compounds having sufficient electrophilic character toreact with the metallated ethylene polymer which is nucleophilic. Ifmore than one reagent is used, they may be added either sequentially orsimultaneously. In addition, steps (2) and (3) may be reversed withoutadverse effects.

In a third aspect, the present invention is a graft copolymer whichexhibits thermoplastic elastomer properties, said graft copolymercomprising an ethylene polymer backbone with at least two pendantpolymer chains, the ethylene polymer having polymerized thereinethylene, a nonconjugated diene and at least one 1-olefin having threeor more carbon atoms, the pendant polymer chains (a) having a numberaverage molecular weight of from about 500 to about 100,000, (b) beingformed by polymerizing at least one monomer selected from the groupconsisting of anionically polymerizable monomers which, afterpolymerization, form heterogeneous domains when two or more of suchpendant chains are proximate to each other, and (c) comprising fromabout 10 to about 60 percent by weight based on copolymer weight.

Beneficially, at least about fifty percent of the polymer molecules havetwo or more pendant polymer chains attached thereto.

In a fourth aspect, the present invention is a process for preparing agraft polymer having an ethylene polymer backbone and a plurality ofside chains which comprises: (a) providing a metallated ethylenepolymer; (b) contacting the metallated polymer with a modifying compoundselected from the group consisting of alpha-methylstyrene,alpha-ethylstyrene, alpha-propylstyrene and alpha-isopropylstyrene underreactive conditions to form a modified polymer; and (c) contacting themodified polymer with at least one reagent selected from the groupconsisting of compounds having sufficient electrophilicity to react withthe modified polymer under reactive conditions sufficient to form thegraft polymer. If more than one reagent is used, they may be addedeither sequentially or simultaneously.

The metallated polymer, if in the form of a generally homogeneoussolution, is desirably diluted with about 10% by volume or more of apolar solvent before adding the modifying compound. The polar solventmay, however, be added either simultaneously with, or subsequent to, themodifying compound provided addition is complete before contacting themodified polymer with one or more reagents. The solvent must besubstantially nonreactive with the modifying compound and the metallatedpolymer, both before and after modification. The metallated ethylenepolymer is nucleophilic even after modification.

The metallated polymers suitable for use in the fourth aspect of thepresent invention are desirably prepared in accordance with the processof the first aspect of the present invention. Satisfactory results areobtained, however, when other processes, such as those described by Ducket al. or Halasa et al., are used to prepare the metallated polymer.

In a fifth aspect, the present invention is a graft copolymer havingthermoplastic properties and comprising a preformed ethylene polymerbackbone having randomly attached thereto at least two pendant polymerchains, the pendant polymer chains comprising from about 10 to about 60percent by weight, based on copolymer weight, and having (a) a numberaverage molecular weight of from about 500 to about 100,000 (b)polymerized therein at least one moiety of a modifying compound, themoiety being connected to the preformed polymer backbone, and at leastone monomer selected from the group consisting of anionicallypolymerizable monomers.

The aforementioned graft copolymers have a structure similar toconventional linear triblock or radial multiblock polymers.Beneficially, at least about fifty percent of the polymer molecules havetwo or more pendant polymer chains attached thereto by way of at leastone moiety of a modifying compound.

In a sixth aspect, the present invention is a three-componentmetallating composition which comprises a tertiary amine, a potassiumalkoxide and at least one lithium alkyl, the components being present inamounts sufficient to provide a molar ratio of tertiary amine to lithiumatom of from about 0.2 to about 5 and a molar ratio of potassium atomsto lithium atoms of greater than about 0.5. The ratio of potassium atomsto lithium atoms is beneficially greater than about 1, desirably fromabout 1 to about 4. The metallating composition is suitable formetallation of polymers containing varying degrees of unsaturation. Thecomposition is particularly suitable for metallating copolymers ofethylene and a nonconjugated diene and interpolymers of ethylene, anonconjugated diene and at least one 1-olefin having three or morecarbon atoms.

The present invention also relates to the metallated ethylene polymersprepared as herein described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are graphic portrayals of the data presented in Table I.Table I is a compilation of metallation trials for Examples 1-6 andComparative Examples A-T. The vertical axis represents percent of dienemetallated (also referred to as "percent ene conversion."). Thehorizontal axis represents the molar ratio of potassium (K) atoms tolithium (Li) atoms in the metallating reagents (FIG. 1) or the molarratio of tetramethylethylenediamine (TMEDA) to lithium atoms in themetallating reagents (FIG. 2). In FIG. 1, Curve A represents a molarratio of TMEDA/Li of 0.0, Curve A' is an algebraic addition of the curvein FIG. 2 and Curve A; Curve B represents a molar ratio of TMEDA/Li of0.5; and Curve C represents a molar ratio of TMEDA/Li of 1.0.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Suitable ethylene polymers include ethylene/nonconjugated dienecopolymers and interpolymers of a nonconjugated diene, ethylene and atleast one mono-olefin having a single terminal ethylenic group and threeor more carbon atoms. The copolymers beneficially have polymerizedtherein, based upon copolymer weight, from about 90 to about 99.9percent ethylene and from about one-tenth to about ten percentnonconjugated diene. The copolymers desirably have polymerized thereinfrom about one to about six percent nonconjugated diene and from about94 to about 99 percent ethylene. Useful interpolymers have polymerizedtherein, on a polymer weight basis, from about 15 to about 99.5 percentethylene, from about 0 to about 85 percent mono-olefin other thanethylene and from about 0.5 to about 10 percent nonconjugated diene. Theinterpolymers beneficially have polymerized therein, on a polymer weightbasis, from about 40 to about 80 percent ethylene and from about 1 toabout 8 percent non-conjugated diene, with the balance comprising theother mono-olefin(s).

The mono-olefins (1-olefins) beneficially have from three to abouttwenty carbon atoms. Desirable 1-olefins contain from three to tencarbon atoms. Preferred 1-olefins include propylene, butene-1, hexene-1and octene-1.

The nonconjugated dienes are selected from the group consisting ofstraight or branched chain diolefins, cyclic diolefins and bicyclicdiolefins. The straight or branched chain nonconjugated diolefinsbeneficially have from five to about twenty carbon atoms. The straightor branched chain nonconjugated dienes desirably have from five to aboutten carbon atoms.

The straight or branched chain nonconjugated diolefins include those inwhich both double bonds are terminal as well as those in which only onedouble bond is terminal. Straight or branched chain nonconjugated dieneswherein both double bonds are terminal include 2-methyl-1,5-hexadiene,3,3-dimethyl-1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene,1,8-nonadiene, 1,9-decadiene, 1,19-eicosadiene and the like. Straight orbranched chain diolefins wherein only one double bond is terminalinclude 1,4-hexadiene, 1,4-heptadiene, 1,5-heptadiene and the like.

The cyclic nonconjugated diolefins suitably have from about five toabout twenty carbons. Illustrative cyclic diolefins includecyclohexadiene, cycloheptadiene, cyclooctadiene and the like.

The bicyclic nonconjugated dienes suitably have from about ten to aboutthirty carbon atoms. Typical bicyclic, or bridged ring, diolefinsinclude dicyclopentadiene, ethylidene norbornene, norbornadiene and thelike.

The nonconjugated diene is desirably selected from the group consistingof 1,4-hexadiene and ethylidenenorbornene.

Methods of preparing EPDM polymers are disclosed in a number of UnitedStates patents. A partial listing of such patents includes Nos.2,933,480; 3,000,866; 3,063,973; 3,093,621; 3,260,708; 3,280,082; and3,310,537. The teachings of these patents are incorporated herein byreference.

Copolymers of ethylene and at least one nonconjugated diene monomer arereadily prepared under slurry conditions via Ziegler catalysis. Slurryconditions and suitable catalysts are generally the same as those usedin polymerization of ethylene. Differences, if any, are readilydetermined without undue experimentation.

Metallation occurs readily when the ethylene polymer is in solution.Metallation will also occur when the ethylene polymer is dispersed in asolvent as a slurry of finely-divided particles if the particles areadequately wetted with the solvent. The solvents are beneficiallynonpolar, saturated hydrocarbons which solvate, but do not react with,the ethylene polymer, either before or after metallation, or withmaterials used to metallate the ethylene polymer. The solvent isdesirably free of moisture, air and any impurities which might reactwith metallation reagents. Preferred solvents for the ethylene polymerare saturated hydrocarbons having from about 5 to about 10 carbon atoms,such as hexane and cyclohexane.

Useful tertiary diamines have three saturated aliphatic hydrocarbongroups attached to each nitrogen and include, for example, (a) chelatingtertiary diamines, (b) cyclic diamines and (c) bridgehead diamines. Thechelating tertiary diamines are desirably represented by the formulaR'R"N--C_(x) H_(2x) --NR"'R"" where each R can be a straight- orbranched-chain alkyl group of any chain length containing up to 20carbon atoms or more, all of which are included herein, and x can be anywhole number from 2 to 10. The ethylene diamines in which all alkylsubstituents are the same are of particular interest. The latterinclude, for example tetramethylethylenediamine,tetraethylethylenediamine, tetradecylethylenediamine and the like.Cyclic diamines include tetralkyl 1,2-diamino cyclohexanes, tetralkyl1,4-diamino cyclohexanes, piperazine, N,N'-dimethylpiperazine and thelike. Bridgehead diamines include sparteine, triethylenediamine and thelike.

Tertiary monoamines such as triethylamine are generally not veryeffective in this reaction. However, bridgehead monoamines such as1-azo(2,2,2)bicyclooctane and its substitued homologs such as the4-methyl and 4-ethyl substituted derivatives thereof are quiteeffective.

The potassium alkoxides include alkyl and aryl alkoxides having up toabout 20 carbon atoms in which potassium is bound to a hetero atom.Suitable alkoxides include potassium methoxide, potassium ethoxide,potassium butoxides such as potassium-tert-butoxide, potassiumphenoxide, potassium-tert-amyloxide (also known aspotassium-tert-amylate), potassium naphthoxide and the like. Thepotassium alkoxide is desirably either potassium-tert-butoxide orpotassium-tert-amyloxide.

The lithium alkyl compounds are represented by the general formulaRLi_(x), wherein R is (a) a saturated hydrocarbon radical which usuallycontains no more than 20 carbon atoms; (b) an aromatic radical such asphenyl, naphthyl, tolyl, methyl-naphthyl and the like; or (c) asaturated cyclic hydrocarbon radical having, for example, from five toseven carbon atoms. In addition, R can be a mono-unsaturated cyclichydrocarbon radical having, for example, from five to seven carbonatoms, an unconjugated unsaturated aliphatic radical of one to twentycarbon atoms or an alkyllithium compound having one or more aromaticgroups on the alkyl group. In the general formula, x=1 to 3.Representative compounds of the formula RLi_(x) include, for example:

methyllithium

i-propyllithium

sec-butyllithium

n-butyllithium

t-butyllithium

n-dodecyllithium

phenyllithium

4-phenylbutyllithium

4-butyl-cyclohexyllithium

alpha- and beta-naphthyllithiums

any biphenyllithium

styryllithium

benzyllithium

indanyllithium

1-lithio-3-butene

1-lithio-cyclohexene-3

1-lithio-cyclohexene-2

1,4-dilithiobutane

1,4-dilithiobenzene

1,3,5-trilithiopentane

1,3,5-trilithiobenzene

Lithium adducts of polynuclear aromatic hydrocarbons, as described inU.S. Pat. No. 3,170,903, can also be employed. Illustrative polynucleararomatic compounds include biphenyl, naphthalene, anthracene andstilbene.

Surprisingly, primary and secondary alkyllithium compounds in which thealkyl group is branched or cyclic (hereinafter "branched alkyllithiumcompounds") are generally more effective, in terms of metallationefficiency, than alkyllithium compounds in which the alkyl group islinear. The branched alkyllithium compounds may be used singly, inadmixture with other branched alkyllithium compounds or in admixturewith linear alkyllithium compounds. Selection of a particular branchedalkyllithium compound, or admixture thereof with other alkyllithiumcompounds, depends upon factors such as cost, efficiency, availabilityand the like. Suitable branched alkyllithium compounds have five or morecarbon atoms per alkyl moiety. Desirable branched alkyllithium compoundsinclude 3,3-dimethylbutyllithium, 3,3-dimethylpentyllithium,menthyllithium and neopentyllithium.

The tertiary diamine, the potassium alkoxide and the lithium alkyl arepresent in amounts sufficient to provide a molar ratio of tertiarydiamine to lithium atom of from about 0.2 to about 5 and a molar ratioof potassium atoms to lithium atoms of greater than about 0.5,beneficially greater than about 1. The molar ratio of potassium atoms tolithium atoms is desirably from about 1 to about 4.0, preferably fromabout 1.0 to about 3.7. The combined amounts of potassium alkoxide,lithium alkyl and tertiary diamine are also sufficient to provide adegree of metallation (percent ene conversion) which exceeds thatprovided by (a) the potassium alkoxide and the lithium alkyl or (b) thetertiary diamine and the lithium alkyl. The degree of metallation fromthe combined amounts also exceeds the sum of (a) and (b).

The polar solvents are suitably Lewis bases such as ethers and amines.Illustrative Lewis bases include tetrahydrofuran,2-methyl-tetrahydrofuran, 2,5-dimethyltetrahydrofuran, diethyl ether,triethyl phosphine, triethylamine, dimethyl ether, ethyl methyl ether,ethylene glycol dimethyl ether (glyme), diethylene glycol dimethyl ether(diglyme). The polar solvent is desirably tetrahydrofuran, ethyleneglycol dimethyl ether or diethylene glycol dimethyl ether.

Metallation of ethylene polymers, in accordance with the presentinvention, is accomplished in a process which comprises three steps:first, providing an admixture of the ethylene polymer and a saturatednonpolar hydrocarbon solvent; second, forming an intermixture of theadmixture and activating amounts of a tertiary diamine and a potassiumalkoxide; and third, contacting the intermixture with an amount of atleast one lithium alkyl (also referred to as "alkyllithium") compoundunder conditions sufficient to provide a lithiated polymer. Theadmixture may be prepared in advance or mixed in situ. The tertiarydiamine and the potassium alkoxide may be added either separately or asa combination. In the event they are added separately, the order ofaddition is unimportant. The second and third steps may be reversedwithout adverse effect upon the resultant metallated ethylene polymer.

The amount of alkyllithium compound is sufficient to provide more thanabout twenty percent of the polymer molecules with at least onelithiated site. The amount can be increased to provide up to aboutninety percent and more of the molecules with at least one lithiatedsite. The amount will vary depending upon a number of factors, one ofwhich is degree of functionalization required for a given end use.Reducing the amount to provide less than twenty percent of the moleculeswith at least one lithiated site, while possible, is believed to beimpractical due to insufficient polymer property modification.

Metallation is carried out at a temperature of from about 10° Centigradeto about 90° Centigrade. The temperature is beneficially from about 20°Centigrade to about 50° Centigrade. Higher temperatures are normallyundesirable since side reactions, polymer degradation and decompositionof the alkyllithium compounds are likely to occur.

Although the amount of lithium alkyl compound may be varied, two pointsare noteworthy. First, excess lithium alkyl compounds will compete withthe metallated polymer for anionically polymerizable monomers or otherreagents which are added to the metallated polymer to prepare a graftedor functionalized ethylene polymer.

The polymerizable monomers will react with excess lithium alkylcompounds to form homopolymer if only one monomer is added,interpolymers if two or more monomers are added, or other reactionproducts depending upon the nature and amounts of reagents. Ifinterpenetrating networks or mixtures of polymers are either acceptableor desirable, elimination of excess lithium alkyl compounds isunnecessary. If interpenetrating networks or mixtures are not desired,care should be taken to avoid such an excess. Second, an insufficientamount of lithium alkyl will not provide desirable ethylene polymerproperty modification via grafting.

The nonpolar hydrocarbon solvent is desirably free of impurities whichwill react with metallating reagents. Small levels of impurities may be"blanked" with a lithium alkyl compound before starting the second stepof the metallation procedure set forth herein. This is done to minimizereaction with the ethylene polymer's double bonds. These double bondsare, in general, substantially unaffected by lithium alkyls withoutother reagents being present.

The term "blanking", as used herein, denotes a procedure wherein aprecise amount of active reagent is added to react with the impuritiesto render them chemically inactive. In a typical procedure, an aliquotof the solvent or admixture is mixed with a compound which will show aperceivable change, e.g., a color change, upon addition of the activereagent. Diphenylethylene, when added to the solvent or admixture, willcolor the solvent or admixture yellow when active carbanions arepresent. The solvent or admixture will be colorless in the absence ofactive carbanions. Titration of the diphenylethylene-containing solventor admixture with an active reagent, such as n-butyllithium, allowscalculation of the precise molar amount of active reagent needed toneutralize the reactive impurities.

Preparation of graft polymers suitably follows metallation of theethylene polymer. The metallated ethylene polymer may, as noted herein,be in the form of (a) a slurry of wetted particles or (b) a homogeneousmixture. Procedures used in grafting will vary depending upon the formin which the matallated polymer is available.

If the metallated polymer is in the form of a homogeneous mixture,grafting may be accomplished without recovery of the metallated polymerfrom the solvent and reagents used in preparing the metallated polymer.Grafting comprises two steps: first, diluting the metallated polymersolution with a polar solvent which is substantially nonreactive withthe metallated polymer; and second, blending at least one reagent withthe metallated polymer solution under reactive conditions. If viscosityof the metallated polymer solution is so high that dispersion of thereagent(s) therein is difficult, if not impossible, then the order ofthe steps must be as stated. If the viscosity of the metallated polymersolution is sufficiently low to provide for adequate dispersion of thereagent(s) therein, the steps may be reversed without adverse results.

Polar solvents are generally more effective than nonpolar solvents interms of reducing mixture viscosity. The polar solvents, in addition toacting as a diluent, are believed to prevent ionic interaction betweenadjacent metallated polymer molecules. The polar solvents alsoaccelerate subsequent graft polymerization reactions. Nonpolar solventsmay be used if desired.

Satisfactory results have been obtained when the viscosity modifyingamount is greater than about ten percent volume of all solvents in themixture. Lesser amounts may be used if the mixture viscosity issufficiently low. Amounts of twenty percent by volume and greater alsoproduce acceptable results, but are not needed.

Addition of the polar solvent is desirably delayed until aftermetallation of the ethylene polymer is substantially complete. Thoseskilled in the art of metallation chemistry recognize that the polarsolvents are metallated under conditions whereby the ethylene polymer ismetallated. The metallated polar solvent is an undesirable reactant. Italso reduces the amount of available metallating reagent, therebylowering polymer metallation efficiency.

If necessary, the polar solvent may be added before metallation of theethylene polymer is substantially complete provided no more than a brieftime interval elapses before addition of one or more reagents is begun.The length of the time interval varies with completeness of metallation,with metallating components and with reactivity of added reagents. Itis, however, readily determined without undue experimentation.

Addition of the polar solvent before metallation is substantiallycomplete, while permitted, does have some adverse side effects. First,too much polar solvent is metallated if addition of the reagents is notstarted soon enough. As noted herein, the metallated polar solvent is anundesirable contaminant. Second, some of the reagents may be convertedto homopolymers of copolymers rather than being grafted onto theethylene polymer.

Preparation of graft polymers using ethylene polymers in the form of aslurry may be accomplished either by duplicating the procedure set forthherein for ethylene polymers in the form of a homogeneous mixture or byfollowing a modified procedure. The modified procedure is the same asthe former procedure through metallation of the ethylene polymer. Aftermetallation is substantially complete, the solvent and metallationreagents are easily decanted, or filtered, from the metallated polymer.The metallated polymer is then reslurried with fresh solvent.

Reslurrying the metallated polymer in fresh solvent removessubstantially all of the metallation reagents. Accordingly, the freshsolvent need not be the same as that used in metallation and solventsnot previously suitable may be used. The solvent must, however, besubstantially nonreactive with the metallated polymer. Illustrativeadditional solvents include saturated aliphatic solvents and aromaticsolvents.

Polar solvents, particularly suitable for preparing graft polymers insolution, are not required when preparing graft polymers in slurry. Whenthe metallated polymer is in the form of a slurry, it is actually adispersion of discrete particles and ionic interaction, if present, isbelieved to be minimal and of no consequence. Although not needed forpurposes of dilution or preventing ionic interaction, polar solvents maystill be used to accelerate subsequent grafting.

Reagents used in preparing a graft polymer must have sufficientelectrophilic character to react with the nucleophilic metallatedethylene polymer. Anionically polymerizable monomers having sufficientelectrophilic character include, but are not limited to, vinyl aromaticcompounds such as styrene, alpha-methyl styrene and vinyl toluene andits isomers; vinyl unsaturated amides such as acrylamide,methacrylamide; N,N-dilower alkyl acrylamides, e.g.,N,N-dimethylacrylamide; acenaphthalene; 9-acrylcarbazole; acrylonitrileand methacrylonitrile; organic isocyanates including lower alkyl,phenyl, lower alkyl phenyl and halophenyl isocyanates; organicdiisocyanates including lower alkylene, phenylene and tolylenediisocyanates; lower alkyl acrylates and methacrylates, including methyland t-butyl acrylates and methacrylates; lower olefins, such asethylene, propylene, butylene, isobutylene, pentene, hexane, etc.; vinylester of aliphatic carboxylic acids such as vinyl acetate, vinylpropionate, vinyl octoate, vinyl aleate, vinyl stearate, vinyl benzoate;vinyl lower alkyl ethers; vinyl pyridines; vinyl pyrrolidones; dienesincluding isoprene and butadiene; and lower alkylene oxides. The term"lower" is used above to denote organic groups containing eight or fewercarbon atoms.

Other anionically polymerizable monomers are disclosed in MacromolcularReviews, Volume 2, pages 74-83, Interscience Publishers, Inc. (1967),entitled "Monomers Polymerized by Anionic Initiators". Still othermonomers are disclosed in Anionic Polymerization, ACS Symposium Series166, page 60, American Chemical Society (1981). The teachings of thesereferences are incorporated herein by reference. Additional monomersdisclosed in these publications include vinylnaphthalenes, alkylmethacrylates wherein the alkyl group has up to eighteen carbon atoms,lactones and thiiranes. Suitable monomers not disclosed in eitherpublication include lactams such as caprolactam.

By suitable choice of monomer(s), it is possible to prepare pendantpolymer chains having desired polymer properties. The pendant polymerchains may modify the ethylene polymer sufficiently to render itcompatible or covulcanizable with a corresponding variety of polymerswhich are derived entirely, or predominantly, from the monomer(s) in thependant chains. Graft polymers prepared by reacting one or more monomerswith the metallated ethylene polymer typically have pendant polymerchains which comprise from about 10 to about 60, desirably from about 20to about 40, percent by weight of the graft polymer.

Certain of the graft copolymers prepared in accordance with the presentinvention and comprising an ethylene polymer backbone with at least twopendant styrene polymer chains exhibit thermoplastic elastomerproperties provided certain conditions are met. One condition is thatthe pendant styrene polymer chains have a number average molecularweight which is suitably from about 500 to about 100,000, beneficiallyfrom about 2000 to about 30,000 and desirably from about 5000 to about15,000. A second condition is that total styrene polymer content issuitably from about 10 to about 60, beneficially from about 15 to about40, percent by weight of polymer.

Graft polymerization reactions of the present invention are typicallyconducted at a temperature of -10° Centigrade or higher. A usefulmaximum temperature is 60° Centigrade. A desirable temperature range isfrom about 30° to about 50° Centigrade. The grafting reaction ispreferably started at a temperature within a range of from about 10° toabout 30° Centigrade. The reaction is exothermic and will generatesufficient additional heat to cause the reaction to run at, for example,up to 20° Centigrade higher unless external cooling is applied to removethe additional heat.

One class of thermoplastic elastomers, known generically as triblockcopolymers, generally comprise two styrene polymer end blocks attachedto a central polydiene block. Maurice Morton of the University of Akronobserves, in Volume 15, Encyclopedia of Polymer Science and Technology(1971) at page 514, that, in order to obtain optimum mechanicalproperties in styrene-diene-styrene block copolymers, "the polystyreneblocks must be in the range of 10,000-20,000 molecular weight whereasthe polydiene block should have a molecular weight between 40,000 and100,000." In addition, "the total polystyrene content should be between20 and 40 wt.%". "[T]he lower limit of molecular weight is governed byminimum polystyrene chain length required for formation of heterogeneousdomains while the upper limit is set by viscosity considerations whichcan seriously hamper good separation of these domains."

Diblock polymers generally have much lower tensile strengths thananalogous triblock polymers. For example, a typical styrene-butadienediblock polymer has a tensile strength of about 30 pounds per squareinch (0.207 megapascals (MPa)) whereas an analogousstyrene-butadiene-styrene triblock polymer has a tensile strength ofabout 3000 pounds per square inch (20.7 MPa). Admixtures of diblock andtriblock polymers show decreasing tensile strength values as theproportion of diblock polymer increases. Therefore diblock polymercontent should be minimized if tensile strength is to be maximized.

One means of attaining a lower diblock content is to select metallatingconditions and reagent ratios which increase the number of polymerchains having at least two pendant chains of appropriate molecularweight.

In order to enhance polymer properties other than tensile strength, aminimum amount of diblock polymer may be necessary. The skilled artisancan readily determine the minimum amount as well as an appropriatebalance of conflicting physical properties without undueexperimentation.

Thermoplastic elastomer type products are not restricted to graftedethylene polymers wherein the pendant chains are styrene polymers.Satisfactory results are obtained with other anionically polymerizablemonomers described herein, such as methyl methacrylate, which provideheterogeneous domains of adequate molecular weight and hardness. Weightsof pendant polymer chains and percentage thereof with respect to totalgraft polymer weight, are not necessarily the same as specified forstyrene polymer pendant chains. They are, however, readily determinedwithout undue experimentation.

The metallated ethylene polymer of the present invention are generallynucleophilic, and may be so nucleophilic that they must be reacted witha modifying compound before being used to prepare graft polymers fromcertain monomers. The modifying compound is believed to serve one of twopurposes. One is to direct the attack on reagents or monomers at apreferred site when the anionically polymerizable monomer (electrophilicreagent) to be grafted has two or more reactive sites, as in the case ofalkyl esters of methacrylic acid, and is strongly electrophilic ascompared to the metallated polymer. A second purpose is to minimizetermination reactions in favor of polymerization. For example, alkylesters of methacrylic acid, unless modified in accordance with thepresent invention, terminate rapidly when added to the metallatedpolymer. By minimizing terminations, pendant polymer chains of desirablylengths and molecular weight are more readily obtained. The modifyingcompound is believed to be incorporated into the graft polymer withoutadverse effect. Similar results are obtained by modifying metallatedpolymers produced by other processes such as those described by Duck etal. or Halasa et al.

Monomers having two or more reactive sites include alkyl esters ofalpha, beta-ethylenically unsaturated carboxylic acids. The monomer orreagent is beneficially an alkyl ester of acrylic acid or methacrylicacid. The reagent is desirably an alkyl ester of methacrylic acid suchas adamantyl methacrylate, benzyl methacrylate, butyl methacrylate,sec-butyl methacrylate, tert-butyl methacrylate, cyclohexylmethacrylate, decyl methacrylate, dodecyl methacrylate, 2-ethylhexylmethacrylate, ethyl methacrylate, hexadecyl methacrylate, hexylmethacrylate, isobutyl methacrylate, isopropyl methacrylate,3,5-dimethyladamantyl methacrylate, 3,3-dimethylbutyl methacrylate,3,3-dimethyl-2-butyl methacrylate, 3,5,5-trimethylhexyl methacrylate,methyl methacrylate, octadecyl methacrylate, octyl methacrylate, pentylmethacrylate, phenethyl methacrylate, phenyl methacrylate propylmethacrylate and tetradecyl methacrylate. The reagent is preferablymethyl methacrylate, butyl methacrylate or tert-butyl methacrylate.Other suitable methacrylates include diethylaminoethyl methacrylate,2-N-tert-butylaminoethyl methacrylate, 1H,1H-heptafluorobutylmethacrylate, 1H,1H,7H-dodecafluoroheptyl methacrylate,1H,1H,9H-hexadecafluorononyl methacrylate, 1H,1H,5H-octafluoropentylmethacrylate, 1,1,1-trifluoro-2-propyl methacrylate, isobornylmethacrylate, 4-methoxycarbonylphenyl methacrylate, dimethylaminoethylmethacrylate, and 3-oxabutyl methacrylate.

The modifying compound is beneficially added to a homogeneous mixture ofa metallated polymer after addition of the polar solvent. The solventfacilitates addition of the modifying compound and acids in addition ofmonomers following modification of the metallated polymer. The solventmust be nonreactive with the modifying compound, the metallated polymerand the modified polymer.

The modifying compound is suitably selected from the group consisting oflower alkylene oxides, diphenyl ethylene, alpha-methylstyrene,homologues of alpha-methylstyrene and the like. Homologues ofalpha-methylstyrene include alpha-ethylstyrene, alpha-propylstyrene andalpha-isopropylstyrene. Alpha-methylstyrene is preferred because of itsavailability. Desirable results are obtained when one of thosecompounds, particularly alpha-methylstyrene and its homologues, is addedstoichiometrically with metallated sites on the ethylene polymer. Aone-for-one reaction of a modifying compound with each metallated siteis neither necessary nor practical, even with stoichiometric amounts ofthe modifying compound. The modified polymer, like the metallatedpolymer, functions as an anionic polymerization initiator. In otherwords, the modified polymer competes with the metallated polymer for theremaining modifying compound. In short, the term "modified polymer", asused herein, means that at least some, desirably at least a majorportion, of the metallated sites are modified.

Modification of the metallated ethylene polymer may be accomplishedeither with or without recovery of the metallated polymer from solvents,metallating reagents and the like used in metallating the polymer.

The term "lower alkylene oxide" is used herein to denote one havingeight or fewer carbon atoms. Ethylene oxides and propylene oxides aresuitable for purposes of the present invention.

Graft polymers prepared from modified polymers are generally classifiedas thermoplastic rather than as thermoplastic elastomers. These graftpolymers have pendant chains with a number average molecular weight offrom about 2000 to about 70,000. The pendant polymer chains comprisefrom about 10 to about 40 percent by weight based on copolymer weight.In addition, such graft polymers do not have polymerized therein anyfulvene and fulvene derivative moieties.

The graft polymers prepared from the modified polymers, particularlythose grafted polymers having pendant methyl methacrylate chains, arestructurally analogous to polymers such asstyrene-ethylene/butylene-styrene block polymers which are used inpreparing thermoplastic interpenetrating networks. Poly(methylmethacrylate) and polystyrene have identical solubility parameters, asmeasured in terms of calories per milliliter. The graft polymers shouldtherefore form thermoplastic interpenetrating networks when admixed withengineering thermoplastic polymers such as poly(ethylene terephthalate),poly(butylene terephthalate), styrene-maleic anhydride and polyamides,e.g., nylon 6, nylon 4, nylon 11, nylon 12 and nylon 66.

Graft polymers having pendant methyl methacrylate polymer chains andbeing prepared by the process of the present invention differ from thoseprepared by a free radical grafting process. The latter process resultsin a number of crosslinks and consequent hardening of the graft polymer.Hamad et al. (U.S. Pat. No. 3,622,652) is one reference describing sucha process.

When the graft polymer pendant chains have reached a desired molecularweight, the reaction may be terminated in the same way other anionicpolymerizations are terminated. For example, an alcohol, an acid, orboth may be added to terminate polymerization. As a practical matter,many of the graft polymerization reactions will self terminate. In thoseinstances, alcohol, for example, is added to terminate or kill remaininganionic polymerization sites. The polymer is then recovered byconventional means.

Metallated polymers produced as described herein have uses other thanpreparing the graft polymers described herein. The metallated polymerswill react, in the same manner as organo-alkali metal compounds, with awide variety of reactive chemicals to produce new materials. Fivetypical reactions are described in succeeding paragraphs.

The metallated polymers can be reacted with carbon dioxide. The reactionproduct is neutralized with a mineral acid to produce a carboxylatedpolymer. The degree of carboxylation is dependent upon the amount ofmetallation.

The metallated polymer can be reacted with alkylene oxides to produce anintermediate. The intermediate is terminated with a compound having areactive hydrogen to yield hydroxy-functionalized compounds.

The metallated polymer can be used to initiate the polymerization ofdienes and certain vinylic compounds. Graft copolymers or homopolymerscan thus be prepared by adding lithium-polymerizable monomers to themetallated polymer.

Block compolymers which cannot be produced by any more usual means canbe prepared conveniently by using the metallated polymer as a startingmaterial. A suitable co-reactant is a polymer or polymer segment whichhas a reactive group.

Useful reaction products are prepared by reacting the metallatedpolymers with compounds such as ketones, aldehydes, esters, nitriles,silicon halides, isocyanates, carboxylic acids and salts, carbondioxide, acid chlorides, etc.

One particular class of useful products is obtained by reacting fulvenederivatives with metallated ethylene polymers which have not beenreacted with a modifying compound such as alpha-methylstyrene. Fulvenederivatives suitable for purposes of the present invention arerepresented by the general formula ##STR1## wherein R₁ and R₂ areindependently hydrogen or hydrocarbon groups with one to twelve carbonatoms per group. The hydrocarbon groups are aliphatic, alicyclic oraromatic. R₃ is an alkyl group of from about one to about four carbonatoms. R₁ and R² may also form a cyclic group. Illustrative fulvenederivatives include fulvene, methylfulvene, dimethylfulvene,ethylfulvene, methyl ethylfulvene, methylpropylfulvene,methylisopropylfulvene, methylamylfulvene, diethylfulvene,dipropylfulvene, phenylfulvene, methylphenylfulvene, diphenylfulvene,styrylfulvene, 6,6-cyclotetramethylene fulvene,6,6-cyclopentamethylenefulvene, 6,6-cyclotetramethylene fulvene,6,6-cyclopentamethylenefulvene, 2-methyl-6,6-fulvene,2-ethyl-6,6-fulvene and 3-methyl-6,6-fulvene. The fulvene derivative isdesirably dimethylfulvene.

The fulvene derivatives react very readily with the metallated ethylenepolymers of the present invention at a reaction temperature of fromabout -80° to about 150° Centigrade. The reaction temperature isbeneficially from about -20° to about 50° Centigrade and desirably fromabout 20° to about 50° Centigrade. The reaction time will vary with thereaction temperature, the fulvene derivative, the degree of metallationand the like. Satisfactory results are obtained, for example, withdimethyl fulvene at a reaction temperature of about 25° Centigrade and areaction time of about one hour.

The polymer obtained by reacting a fulvene derivative with themetallated ethylene polymer has a plurality of pendant cyclopentadienyllithium groups attached to the ethylene polymer backbone. Thecyclopentadienyl lithium groups are readily converted to cyclopentadienegroups by treating the polymer with a compound having an activehydrogen, such as water, alcohols and acids.

The polymer containing a plurality of pendant cyclopentadiene groups isquite reactive. As such, it will undergo Diels-Alder crosslinking in thesame manner as monomeric cyclopentadiene.

As noted herein, certain of the graft copolymers prepared in accordancewith the present invention exhibit thermoplastic elastomer properties.These properties are enhanced if the pendant polymer chains are reactedwith a fulvene derivative rather than terminated with alcohol or anacid. Those polymer chains which react with the fulvene derivative willalso undergo Diels-Alder crosslinking. The pendant polymer chains arebelieved to act as an extender enhancing the probability thatcyclopentadiene moieties will come in contact with each other.

Although the disclosure is directed to metallation of ethylene polymers,the metallating composition can be effectively used with other polymershaving varying degrees of unsaturation. Examples of such polymersinclude butyl rubbers prepared by the interpolymerization of isobutyleneand isoprene; polymers of ethylene, higher alpha-olefins, and conjugateddienes such as butadiene, isoprene and the like; polymers prepared bythe interpolymerization of diene monomers with lower (1-8 carbon atoms)alkyl acrylate monomers; and polymers prepared by theinterpolymerization of diene monomers with vinyl ketones, vinyl estersor vinyl ethers. These metallated polymers can then be used to preparegraft polymers or functionalized polymers in the same manner asdisclosed herein with respect to ethylene polymers.

The following examples are for purposes for illustration only and arenot to be viewed as limiting the present invention. All parts andpercentages are on a weight basis unless otherwise indicated. Examplesof the present invention are indicated in Arabic numerals whilecomparative examples are indicated by capital alphabetic letters.

APPARATUS DESCRIPTION

Reactions were run in one of four apparatus. The apparatus differedprimarily in size or capacity and secondarily in terms of components ormaterials of construction. Notwithstanding such differences, thereactions conducted therein followed a single reaction procedure unlessotherwise specified.

The first apparatus, hereinafter "500 Milliliter Reactor", was set up ina dry box under a gaseous nitrogen atmosphere. The apparatus wasassembled from glassware which has been washed and then dried for atleast four hours at a temperature of about 120° Centrigrade. A 500milliliter capacity Tall Form™ breaker was normally used as a reactionvessel. In some instances, the reaction vessel was a 500 millilitercapacity Fleaker™. Both vessels were commercially available from CorningGlass Works. Solutions added to the vessels were agitated using avariable speed, motor-driven, stainless steel stirrer. A slinging diskdeflection plate was disposed on the stirrer to preclude reactionproduce from exiting the vessel by climbing the stirrer when the TallForm™ breaker was used as the reaction vessel. The stirrer motor had anoperating range of 40-315 revolutions per minute (from about 4.2 toabout 33 radians per second).

The second apparatus, hereinafter "600 Milliliter Reactor", wasidentical to the first apparatus except that the vessel was a 600milliliter capacity beaker commercially available from Corning GlassWorks.

The third apparatus, hereinafter "Three Liter Reactor", was based upon a3000 milliliter capacity, O-ring sealed, glass kettle body, commerciallyavailable from Lab Glass Inc. under the trade designation LG-8075. Thekettle body was mated with a thick-walled cover having four ground glassopenings, one in the center and three spaced equally near the peripherythereof. The top was commercially available from Curtin-MathesonScientific, Inc. under the trade designation Pyrex™ 6947. Amultiple-blade turbine agitator equipped with a slinging disk deflectionplate was fitted into the center opening. The agitator blades werepitched at an angle of 45°. The agitator was driven by a motor having anoperating range of from 14 to 150 revolutions per minute (1.47 to 15.71radians per second). A gaseous nitrogen source connected to a bubblerand to one of the peripheral openings was used to establish a gaseousnitrogen atmosphere in the apparatus. A second peripheral opening wasfitted with a rubber septum. The third peripheral opening was fittedwith a polytetrafluoroethylene adapter and thermocouple probe.

The fourth apparatus, hereinafter "Five Gallon Reactor", was a jacketedfive gallon (18.93 liters) stainless steel autoclave. Solvents andmonomers were dispensed from the pressure vessels piped directly to theautoclave. A one quarter inch (0.64 centimeter) ball valve was fittedwith a rubber septum for addition of other reagents. The autoclave wasequipped with a multiple-blade, motor-driven turbine agitator having aslinging disk deflection plate mounted near the top thereof. Theagitator was driven by a motor having an operating range of from about50 to about 150 revolutions per minute (5.24 to 15.71 radians persecond). The agitator blades were pitched at an angle of 45°. A gaseousnitrogen source was connected to the autoclave for the purposes ofpurging the autoclave of water, air and other impurities andestablishing a nitrogen atmosphere therein. The autoclave was alsofitted with block valve vents to allow (a) normal depressurization and(b) near atmospheric pressure addition of reagents under a nitrogenpurge. In addition, the autoclave was fitted with temperature sensingdevices.

GENERAL METALLATION PROCEDURE

In a typical reaction with the 500 Milliliter Reactor, one hundredmilliliters of a stock solution of an EPDM terpolymer in cyclohexane wasadded to the reactor vessel. The stock solution was diluted to 300milliliters total volume with cyclohexane. The EPDM terpolymer has anominal propylene content of about 39 percent of terpolymer weight, anominal 1,4-hexadiene content of two percent of terpolymer weight and aMooney viscosity (ML 1+4 at 121° Centrigrade) of 20. Nominal dienecontent was calculated based upon Carbon-13 Nuclear Magnetic ResonanceSpectroscopy. The terpolymer had a peak molecular weight, determined bygel permeation chromatography at 135° Centrigrade, of 102,067. Theterpolymer was commercially available under the trade designationNordel™ 1320 from E. I. duPont de Nemours & Co.

Metallating reagents were added volumetrically to the stirred stocksolution. The metallating reagents were of three types-lithium alkyls,potassium alkoxides, and tertiary diamines. The potassium alkoxides werepresent as one to two percent solutions in cyclohexane. The lithiumalkyls were present as nominal 1.5 to 3 Molar solutions in hexane. Thetertiary diamines were undiluted. The potassium alkoxide and thetertiary diamine were added to the stirred solution which was maintainedat a temperature of about 30° Centigrade. The lithium alkyl was thenadded to the stirred solution.

Prior to additon of the lithium alkyl, the stirred solution was clearand colorless. Following addition of the lithium alkyl, the solutionusually became cloudy. As metallation proceeded, the cloudinessdisappeared and the solution became colored. Typical colors were shadesof brown, reddish brown or orange. In some instances, where either ahigh tertiary diamine to lithium ratio or a highly branched lithiumalkyl was used, little or no cloudiness was observed.

Metallation reactions were usually either terminated or reacted with areagent about one hour after addition of the lithium alkyl to thestirred solution. Gel formation usually occurred before termination. Itis believed that gel formation was due to ionic crosslinking. Theslinging disk deflector plate kept the gel from climbing the shaft andexiting the reaction vessel.

Metallation reactions using the Three Liter Reactor generally duplicatedthe procedure detailed hereinafter for the Five Gallon Reactor. Theamounts of polymer, solvents, reagents, and the like were increased dueto the change in capacity. In addition, the reaction temperature was 25°Centigrade rather than 30° Centigrade. Additional differences arestated, where appropriate, in the examples which follow.

Metallation Reactions using the Five Gallon Reactor differed in severalaspects from the procedure detailed for the 500 Milliliter Reactor.First, the ethylene polymer was not added as a stock solution. Rather,the ethylene polymer and the solvent were added separately to thereactor to form a slurry. The slurry was then agitated and heated to atemperature of 70° Centigrade. Heating and agitation were continued fora period of about two hours, or until the polymer was adequatelydissolved. The reactor and its contents were then cooled to atemperature of about 25° Centigrade and allowed to stand, withoutagitation, overnight (about eighteen hours). Second, metallatingreagents were added to the reactor via a different technique. Inside anitrogen-filled dry box, the reagents were volumetrically measured andplaced in individual bottles which were then sealed with a rubberseptum. The reagents were transferred to the reactor via a stainlesssteel transfer needle and a small (1/4 inch or about 0.64 centimeter)addition port in the reactor. A small overpressure (about three poundsper square inch gauge or 20.68 kilopascals) of gaseous nitrogen was usedto force the reagents from the bottles into the reactor. The reactor wasthen re-sealed. The reactor and its contents were heated to atemperature of 45° Centigrade during reagent addition.

The reactor temperature was reduced to a set point of 30° Centigradeabout 45 minutes after addition of the metallating reagents. The actualtemperature of the reactor contents was measured fifteen minutes laterand found to be 36° Centigrade. Details of analysis, further reactionsand product recovery are furnished with examples which used the FiveGallon Reactor.

DETERMINATION OF EXTENT OF METALLATION

Direct measurement of lithium metal content of a metallated polymer isgenerally recognized as difficult, if not impossible. Accordingly, anumber of indirect techniques are used. One technique involvescarbonation of the metallated polymer with pure carbon dioxide toproduce a derivative polymer whch can be isolated and titrated as acarboxylic acid. Another technique, which is used herein, involvesreacting the metallated polymer with chlorotrimethylsilane andthereafter determining bound silicon content.

In a nitrogen-filled dry box, a solution of an excess oftrimethylchlorosilane in tetrahydrofuran was added to the metallatedpolymer to provide a pale yellow, silicon-tagged polymer solution. Thesilicon-tagged polymer solution was removed from the dry box and pouredinto an equal volume of a stirred 20/80 (volume ratio) hydrochloricacid/propanol solution to form a mixed solution. Water was added to themixed solution to double the volume thereof. The diluted mixed solutionwas stirred vigorously and then allowed to stand and separate into twoimmiscible layers, an upper organic layer and a lower aqueous/alcohollayer. The organic layer was poured into isopropanol to precipitate thesilicon-tagged polymer out of solution. The polymer was separated fromthe solution by filtration, washed with propanol, separated once againby filtration and then dried in a vacuum oven at a temperature settingof 60° Centigrade. Drying times varied from as short as four hours to aslong as eighteen hours, with the norm being overnight or about sixteenhours.

The dried polymer was compression molded into thin film samples using aheated hydraulic press equipped with a six and one-half inch (16.51centimeter) diameter ram. A sample of the polymer was pressed betweentwo fluorinated polymer film sheets without a frame or chase. The presswas commercially available from Pasadena Hydraulics Incorporated. Thepolymer sample and the film sheets were placed in the press andpreheated to a temperature of from about 150° to about 190° Centigradefor a period of two minutes. The ram was then activated to place a totalforce of 25,000 kilograms of force upon the polymer sample. The forcewas sufficient to form a film sheet having a thickness of from about 1.5to about 3 miles (0.0381 to about 0.0762 millimeters). The thickness wasusually about 2 mils (0.0508 millimeters). The press was then cooled toambient temperatures to allow deactivation of the ram and removal of thefilm samples.

The thin film samples were analyzed for silicon atom content using aninfrared spectrophotometer commercially available under the tradedesignation Model 283 from Perkin Elmer Corporation. A twelve minutescan time over a range of from about 4000 to about 200 reciprocalcentimeters (cm⁻¹) was used for each sample. The extent of metallationwas determined by measuring the intensity of the peak at 850 cm⁻¹, whichrepresented the Si--CH₃ stretch, and the intensity of the peak at 1150cm⁻¹, which represented the C--CH₃ stretch. By comparing the former withthe latter in a ratio (hereinafter "Absorbance Ratio"), errors due tofilm thickness were minimized, if not eliminated. By linear regressionanalysis of a number of Absorbance Ratios versus their measured molarconcentration of trimethyl silane radical (hereinafter "Me₃ Si"), alinear approximation was established whereby a calculated Me₃ Si molarconcentration (hereinafter "(Me₃ Si)_(m) ") could be calculated given anAbsorbance Ratio. Using hexyltrimethylsilane in unmetallated EPDM (thesame EPDM as metallated herein) as a standard, the linear approximationwas found to be: (Me₃ SI)_(m) =(Absorbence Ratio×0.11286)+0.00137.

Percent Ene Conversion was determined by the following equation:##EQU1## The molecular weight of the diene monomer in Nordel™ 1320 was0.08215 grams per millimole.

The EPDM terpolymer most frequently used had a nominal propylene contentof about 39 percent of terpolymer weight, a nominal 1,4-hexadienecontent of two percent of terpolymer weight and a Mooney viscosity (ML1+4 at 121° Centigrade) of 20. Nominal diene content was calculatedbased upon Carbon-13 Nuclear Magnetic Resonance Spectroscopy. Theterpolymer had a peak molecular weight, as determined by gel permeationchromatography at 135° Centigrade, of 102,067. The terpolymer wascommercially available under the trade designation Nordel™ 1320 from E.I. duPont de Nemours & Co.

DETERMINATION OF CONTENT OF ALKYL ESTER OF METHACRYLIC ACID FOLLOWINGGRAFTING

After subjecting metallated polymers to graft polymerization conditions,the resultant polymer was recovered, dried and compression molded intothin film samples using the procedure detailed for preparation of thinfilms containing silicon atoms. The thin film samples were analyzed forpolymethylmethacrylate (PMMA) content using an infraredspectrophotometer commercially available under the trade designationModel 283 from Perkin Elmer Corporation. A twelve minute scan time overa range of from about 4000 to about 200 reciprocal centimeters (cm⁻¹)was used for each sample. The extent of metallation was determined bymeasuring the intensity of the peak at 950 cm⁻¹, which represented anO--CH₃ stretch of the methylmethacrylate, and the intensity of the peakat 1380 cm⁻¹, which represented the CH₂ --CH₂ stretch. By comparing theformer with the latter in a ratio (hereinafter "Absorbance Ratio"), anyerrors due to film thickness were minimized, if not eliminated. Bylinear regression analysis of a number of Absorbance Ratios versus theirmeasured weight percent of PMMA, a linear approximation was establishedwhereby PMMA weight percent could be calculated given the AbsorbanceRatio. Using methylmethacrylate homopolymer in unmetallated EPDM (thesame EPDM as metallated herein) as a standard, the linear approximationwas found to be: PMMA weight percent=(Absorbance Ratio×50.4)+9.62. Thelinear approximation was found to be correct within ±five percent.

EXAMPLES 1-5 AND COMPARATIVE EXAMPLES A-U METALLATION RESULTS

A number of samples of EPDM (Nordel™ 1320) were metallated as hereindescribed with the 500 Milliliter Reactor using varying amounts ofmetallating reagents. The reagents used were (a) n-butyllithium as thealkyllithium; (b) potassium-tert-amyloxide as the potassium alkoxide;and (c) TMEDA as the tertiary diamine. The metallated polymers weretagged with a silane compound as described herein, recovered and formedinto compression molded films which were analyzed via infraredspectroscopy, also as herein described. Results of the analysis togetherwith calculated percentages of diene double bonds converted (% EneConv.) and molar ratios of potassium atoms to lithium atoms (K/Li) andtertiary diamine to lithium atoms (TMEDA/Li) are shown in Table I.

                                      TABLE 1                                     __________________________________________________________________________    METALLATION RESULTS - COMPARISON OF REAGENT COMBINATIONS                      Example/   EPDM           Millimoles Added                                                                         % Ene                                    Comparative Example                                                                      (grams)                                                                            K/Li                                                                             TMEDA/Li                                                                             Li K  TMEDA                                                                              Conv.                                    __________________________________________________________________________    A          6.4  0.5                                                                              0.5    1.40                                                                             0.70                                                                             0.70 11.0                                     B          6.2  0.5                                                                              1.0    1.36                                                                             0.68                                                                             1.36 11.0                                     C          6.4  0.5                                                                              0      1.40                                                                             0.70                                                                             0.00  6.0                                     1          6.4  1.0                                                                              0.5    1.40                                                                             1.40                                                                             0.70 27.0                                     2          6.2  1.0                                                                              1.0    1.36                                                                             1.36                                                                             1.36 43.0                                     D          6.4  1.0                                                                              0      1.40                                                                             1.40                                                                             0.00 17.0                                     3          6.4  2.0                                                                              0.5    1.40                                                                             2.81                                                                             0.70 36.0                                     4          6.2  2.0                                                                              1.0    1.36                                                                             2.72                                                                             1.36 50.0                                     E          6.4  2.0                                                                              0      1.40                                                                             2.90                                                                             0.00 18.0                                     F          6.4  2.8                                                                              0      1.40                                                                             3.90                                                                             0.70 20.0                                     G          6.4  3.0                                                                              0      1.40                                                                             4.30                                                                             0.00 32.0                                     5          6.4  3.0                                                                              0.5    1.40                                                                             4.30                                                                             0.70 54.0                                     H          6.4  3.5                                                                              0      1.40                                                                             4.90                                                                             0.00 39.0                                     I          6.4  3.9                                                                              0      1.40                                                                             5.46                                                                             0.00 60.0                                     J          6.4  4.0                                                                              0      1.40                                                                             5.80                                                                             0.00 70.0                                     K          6.4  4.0                                                                              0.5    1.40                                                                             5.62                                                                             0.70 68.0                                     L          6.2  4.0                                                                              1.0    1.36                                                                             5.44                                                                             1.36 67.0                                     M          6.4  6.7                                                                              0      1.40                                                                             9.36                                                                             0.00 94.0                                     N          6.4  6.7                                                                              0.5    1.40                                                                             9.36                                                                             0.70 84.0                                     O          6.4  6.7                                                                              3.4    1.40                                                                             9.36                                                                             4.68 67.0                                     P          6.2  0  0      1.36                                                                             0.00                                                                             0.00  6.0                                     Q          6.4  0  0.5    1.40                                                                             0.00                                                                             0.80  5.0                                     R          6.2  0  1      1.36                                                                             0.00                                                                             1.36  3.0                                     S          6.4  0  2      1.40                                                                             0.00                                                                             2.90  6.0                                     T          6.4  0  4      1.40                                                                             0.00                                                                             5.80  2.0                                     U          6.4  0  7.25   1.40                                                                             0.00                                                                             10.19                                                                               4.0                                     __________________________________________________________________________

The data presented in Table I and graphically portrayed in FIGS. 1 and 2support several conclusions. First, an alkyllithium compound, eitheralone (Comparative Example P) or in combination with a tertiary diamine(Comparative Examples Q-U) is a relatively inefficient metallatingcomposition at the levels used herein. Second, the combination of analkyllithium compound, a tertiary diamine and a potassium alkoxideexceeds (Examples 1-5) in terms of ene conversion, effectiveness of thetwo component combination of alkyllithium compound and potassiumalkoxide (Comparative Examples C-J & M) at ratios of the latter to theformer of less than about 6.7. Third, the three component combination ofExamples 1-5 exceeds the additive effects of (a) a tertiary diamine andan alkyllithium compound and (b) a potassium alkoxide an an alkyllithiumcompound (Example 1 versus Comparative Examples D and Q or ComparativeExamples B and C as well as Example 2 versus Comparative Examples D andR). Fourth, at ratios of potassium alkoxide to alkyllithium compound ofgreater than about 6.7, the addition of a tertiary diamine actuallyreduces ene conversion percentage. In other words, within a specificrange of component ratios, the three component metallation system of thepresent invention is more effective than combinations of two of thethree components. Similar results are obtained with other metallatingreagents and ethylene polymers, all of which are defined herein.

EXAMPLES 6-9 AND COMPARATIVE EXAMPLE V Preparation of Graft Polymersfrom Metallated Ethylene Polymers

Samples of the same EPDM as used in Examples 1-5 were metallated in theThree Liter Reactor using the equipment and procedures detailed herein.Tetrahydrofuran, in an amount of ten percent by volume, was added to thesolution with stirring to break up gel formation and yield a stirrablesolution. Styrene monomer was added dropwise over a period of about fiveminutes to the dilute solution while the latter was stirred. A dark redcolor, characteristic of a styryl anion was observed. Stirring wascontinued for an additional two hours. In two instances (Examples 7 and9), the reaction was terminated and the product thereof recovered ashereinafter detailed. In two other instances (Examples 6 and 8), anamount of dimethylfulvene was added to the stirred solution. Stirringwas continued for about one hour after which the reaction was terminatedand a reaction product was recovered using the same procedures as withthe product of Examples 7 and 9. In Example 6, the amount ofdimethylfulvene was 11.62 millimoles. In Example 8, the amount was 7.01millimoles. During reaction of the dimethylfulvene, the solution changedfrom the dark red color to white.

The reactions were terminated by adding a 20/80 (volume ratio)hydrochloric acid/isopropanol solution the stirred solution. Thesolution which contained a reaction product was recovered in a two stepprocess. First, the solution was poured into an equal volume of propanolto coagulate the reaction product out of solution. Second, the reactionproduce was mixed with acetone, stirred for about one hour, recovered byfiltration and then dried in a vacuum oven at a temperature setting of60° Centigrade. Drying times were the same as those used in recoveringthe silicon-tagged polymer.

ANALYSIS/PHYSICAL PROPERTY TESTING OF FULVENYLATED POLYMERS COMPOSITION

The graft polymers, with and without fulvene incorporation, wereprepared and analyzed for polystyrene content using a modified versionof the procedures herein described for preparing and analyzingsilicon-tagged polymers. Film samples having a polystyrene contentshowed relatively interference-free peaks at 1948 and 1601 cm⁻¹. Molarconcentration of polystyrene was determined by application of Beer's Lawusing one peak and the appropriate extinction coefficient. Theextinction coefficients were 2.17×10⁴ liters-moles⁻¹ -cm⁻¹ (1601 cm⁻¹peak) and 0.45×10⁴ liters-moles⁻¹ -cm⁻¹ (1948 cm⁻¹ peak). Film thicknesswas measured to the nearest 0.0002 centimeter (cm). Weight percent ofpolystyrene was calculated by iterative calculation which assumed thatthe density of the graft polymer was a linear interpolation of thedensity of the base ethylene polymer and the density of the homopolymerwhich formed the pendant graft.

TENSILE TESTING

The graft polymers of Examples 6-9 were fused and fluxed on a heated(175° Centigrade) two roll mill for two to three minutes until avisually uniform sheet was obtained. The sheet was cut, removed from themill and fit, as a single sheet, into a 10.2×10.2×0.318 centimeter steelchase. The base ethylene polymer (Comparative Example V) was not rollmilled. Instead, shavings of the base polymer were placed in the chase.Press polished sample blanks were formed by compression molding usingthe previously described hydraulic press, heated to a temperature of190° C., and the following schedule: (a) preheat four minutes at 1500kilograms (kg); (b) press two minutes at 25,000 kg; and (c) cool at arate of fifteen degrees Centigrade per minute to ambient temperaturewhile maintaining a total force of 25,000 kg. Tensile Testing was doneusing the general procedures of American Society for Testing andMaterials (ASTM) Test D-412-82, with samples having a thickness of about0.318 cm and being cut from the sample blanks with a type "C" die, and acrossarm separation speed of 25.4 centimeters per minute. Shore AHardness and tensile test results, in terms of Tensile Strength at Breakand Percent Elongation, are shown in Table II.

                                      TABLE II                                    __________________________________________________________________________    PHYSICAL PROPERTY TEST RESULTS - GRAFT POLYMERS                               Example/   Reacted with                                                                           Li/ene                                                                            Percent                                                                              Hardness                                                                           Tensile Strength                                                                       Percent                          Comparative Example                                                                      dimethyl fulvene                                                                       Ratio                                                                             Poly-Styrene                                                                         Shore A                                                                            at Break (MPa)                                                                         Elongation                       __________________________________________________________________________    6          Yes      1.1 27     83   17.86    1100                             7          No       1.1 28     81   13.76    975                              8          Yes      0.6 26     73   4.27     725                              9          No       0.6 29     75   2.71     350                              V          --       --   0     --   0.18     650                              __________________________________________________________________________     *non-metallated EPDM                                                          -- not applicable                                                        

The data presented in Table II illustrates two points. First, it ispossible to prepare graft polymers having thermoplastic elastomerproperties (Examples 7 and 9). Second, it is possible to enhance thethermoplastic elastomer properties of the graft polymers byfulvenylation thereof. Similar results are obtained with othermetallating reagents, ethylene polymers, polymerizable monomers andfulvene derivatives, all of which are defined herein.

EXAMPLE 10 Study of Effect of Lithium Alkyl Structure Upon Metallation

A number of samples of a different EPDM terpolymer than that of Examples1-6 were metallated in the 500 Milliliter Reactor. The proceduredescribed herein under the heading "General Metallation Procedure" wasmodified as follows: (a) the tertiary diamine was omitted; (b) fiftymilliliters of stock solution containing 2.5 grams of EPDM were usedrather than one hundred milliliters; and (c) the stock solution wasdiluted to 200 milliliters total volume rather than 300 milliliters. Thealkyllithium compound was varied from sample to sample. The ratio ofpotassium atoms to lithium atoms was 0.93. The EPDM terpolymer had anominal 1,4-hexadiene diene content of 1.7 percent of terpolymer weightand a Mooney viscosity (ML 1+4 at 121° Centigrade) of 40. The terpolymerwas commercially available under the trade designation Nordel™ 1040 fromE. I. duPont de Nemours & Co. The extent of metallation was determinedas herein described using a different set of constants to determine (Me₃Si)_(m) because of the charge in polymer. With the new constants (Me₃Si)_(m) =Absorbance Ratio×0.10774242+0.00016955. Identity of thealkyllithium compounds together with calculated percentages of dienedouble bonds converted (% Ene Converted) are shown in Table III. Theratio of lithium atoms added per diene double bond was 2.71 for eachsample.

                  TABLE III                                                       ______________________________________                                         METALLATION RESULTS - COMPARISON OF                                          ALKYLLITHIUM COMPOUNDS                                                        Sample                                                                        Identi-                                                                             % Ene                                                                   fication                                                                            Conv.   Alkyllithium Compound(s)                                        ______________________________________                                        a     11.7    n-butyllithium                                                  b     11.7    n-hexyllithium                                                  c     14.5    sec-butyllithium                                                d     18.0    3:1 blend** of 3,3-dimethylbutyllithium & n-butyllithium        e     19.1    isoamyllithium                                                  f     22.4    1:1.5 blend** of 3,3-dimethylbutyllithium &                                   3,3-dimethylpentyllithium                                       g     26.5    3,3-dimethylpentyllithium                                       h     30.6    1:1 blend** of menthyllithium & n-butyllithium                  i     40.9    2:1 blend** of menthyllithium & n-butyllithium                   j*   46.3    4:1 blend** of menthyllithium & n-butyllithium                  k     50.9    neopentyllithium                                                ______________________________________                                         *metallation conducted at 23° Centigrade rather than 30°        Centigrade                                                                    **The ratios are molar ratios                                            

The data presented in Table III demonstrate that, other things beingequal, branched alkyllithium compounds, such as neopentyllithium,metallate ethylene polymers more effectively than generally linearalkyllithium compounds such as n-butyllithium. Although no tertiarydiamine was used during this study, similar results are expected whenthe tertiary diamine is included as in Example 1.

EXAMPLE 11 Metallation of Ethylene-Diene Copolymer With Cyclohexane asthe Solvent

An ethylene-diene copolymer having a nominal 1,4-hexadiene content of2.5 percent, a melt index of 2.5 decigrams per minute and a numberaverage molecular weight of 13,090 was metallated in the 500 MilliliterReactor. Ten grams of the copolymer were refluxed in 300 milliliters ofcyclohexane for ten minutes and then cooled to ambient temperature. Asufficient amount of cyclohexane was added to bring the volume back to300 milliliters. Metallating reagents were added to the solution in theorder stated as follows: (a) 1.0 milliliters (6.65 millimoles) of TMEDA;(b) 2.8 milliliters (3.36 millimoles) of 1.2 molarpotassium-tertamyloxide; and (c) 1.3 milliliters (3.38 millimoles) of2.6 molar n-butyllithium. The solution was stirred and maintained at aconstant temperature of 30° Centigrade throughout metallation.

One hour after addition of the metallating reagents, 3.0 milliliters oftetrahydrofuran were added to the solution. After addition of thetetrahydrofuran, 2.3 milliliters (9.06 millimoles) of 3.94 Molarchlorotrimethylsilane (in tetrahydrofuran) were added to the solution toprovide a silicon-tagged polymer solution.

Twenty milliliters of acidified propanol were added to thesilicon-tagged polymer solution to terminate reaction thereof. Thetagged polymer was then separated from the solution, washed first withpropanol and then with water, separated by filtration and driedovernight in a vacuum oven at a temperature of 60° Centigrade.

The tagged polymer was pressed into a film using the procedure set forthherein and a temperature of 185° Centigrade. The film was analyzed forsilicon atom content by infrared spectroscopy as herein specified.Percent Ene Conversion was calculated using absolute calibration of theformula y=1.86x wherein y=moles per liter of silicon and x=absorbence at850 cm⁻¹ per 0.001 inch (0.0254 millimeter) of thickness. Percent EneConversion was 12.8 percent.

EXAMPLE 12 Metallation of Ethylene-Diene Copolymer With Heptane as theSolvent

With four exceptions, the procedure of Example 11 was duplicated. Oneexception was the replacement of cyclohexane with heptane. A secondexception was the temperature at which the copolymer was refluxed in thesolvent because heptane boils at a higher temperature than cyclohexane.A third exception was based upon visual observation of the polymerparticles before reflux, immediately after reflux and after cooling.With each of the solvents, the polymer particles appeared to swell, orincrease in size while being refluxed and to decrease somewhat in sizewith cooling. A greater amount of swelling was retained after coolingwith heptane as the solvent rather than cyclohexane. A fourth exceptionwas the use of acetone rather than water as a second wash solution.Percent Ene Conversion was calculated to be 23.5 percent.

Examples 11 and 12 demonstrate that an ethylene-diene copolymer can bemetallated. It should be noted that the copolymer is generallycrystalline whereas the EPDM polymers are generally rubbery. Theseexamples also show that the extent of metallation varies according tothe temperature at which metallation is conducted. In other words, theextent of metallation generally increases with increasing temperatureprovided sufficient swelling of the polymer particles occurs and polymerparticle integrity is retained.

EXAMPLE 13 Grafting Polystyrene onto Ethylene-Diene Copolymer

The procedure used in Example 11 was modified in two aspects. First, thecopolymer was initially heated to reflux in heptane then cooled toambient temperature. The solvent was separated from the copolymer,dispersed in cyclohexane, separated a second time, and finally disperseda second time in cyclohexane. Second, metallation was continued for 50minutes rather than one hour. After metallation, three milliliters oftetrahydrofuran and 5.5 milliliters (5 grams) of styrene were added inthe order stated. The temperature increased from 30° Centigrade to 33°Centigrade during reaction of the styrene.

Graft polymerization was terminated by addition of dry ice. The graftpolymer was separated from the solvent, washed twice with acetone, twicewith n-propanol, separated and dried. The dried graft polymer waspressed into a film using the procedure of Example 16. Analysis of thefilm by infrared spectroscopy provided a calculated polystyrene contentof 10.3 percent.

Example 13, while not optimized, clearly shows that grafting ofpolystyrene into an ethylene-diene copolymer is possible. Optimizationis attainable without undue experimentation. Similar results areobtained with other metallating reagents, monomers and other reagentswhich react with the metallated polymer and ethylene copolymers all ofwhich are defined herein.

EXAMPLE 14 Preparation of Grafted Polymer and Determination of GraftingFrequency

The Five Gallon Reactor was used to metallate an EPDM terpolymer andthen react the metallated polymer with styrene monomer. Using thegeneral metallation procedure for the Five Gallon Reactor, 15,142milliliters of cyclohexane solvent and 454 grams the same EPDMterpolymer as used in Examples 1-10 were added to the reactor.Metallating reagents were then added in the order stated: (a) 41.7milliliters of TMEDA; (b) 115.2 milliliters of a 1.2 Molar solution ofpotassium-tert-amyloxide in cyclohexane; and (c) 53.2 milliliters of a2.6 Molar solution of n-butyllithium in hexane. The actual temperatureof the reactor contents after addition of metallating reagents was 46°Centigrade. One hour after addition of the metallating reagents, thetemperature of the reactor contents was found to be 36° Centigrade.

After the temperature measurement, 266 grams of tetrahydrofuran wereadded gravimetrically to the reactor (over a period of about fiveminutes). Five minutes after completing addition of the tetrahydrofuran,200 milliliters of metallated polymer solution were sampled into aseptum-covered bottle and analyzed for extent of metallation via silicontagging as herein described.

About seventeen minutes after completing addition of thetetrahydrofuran, 245 grams of styrene monomer were added gravimetricallyto the reactor contents over a period of eight minutes. The highesttemperature measured after styrene addition was 33° Centigrade.

One hour after beginning addition of styrene monomer, twenty millilitersof n-propyl alcohol were added to the reactor contents to terminatepolymerization and any metallation reactions not previously terminated.The reactor contents were then then transferred to a ten gallon recoveryvessel which contained two gallons of n-propyl alcohol. The vessel wasopen to the atmosphere. The temperature of the n-propyl alcohol wasabout 25° Centigrade. Several pieces of dry ice were added to the vesselcontents while the latter were agitated.

About ten minutes after the dry ice was added, agitation was stopped andthe solid or polymer portion of the vessel contents were allowed tosettle. The polymer portion was recovered by filtration and decantation.The wet polymer portion was washed with several liters of n-propanol andthen recovered by decantation. The wet polymer was then mixed withacetone and agitated for about one hour. The polymer was manually brokeninto small particles during washing and agitation to maximize exposedsurface area. Agitation was then stopped and the polymer was allowed tosettle. A small amount of the liquid was removed and set aside. Theremaining liquid was removed by filtration to leave a solid polymerproduct. The solid polymer product was dried overnight in a vacuum ovenat a temperature of 50° to 60° Centigrade.

The set aside portion of liquid was allowed to evaporate. A solidresidue remained after evaporation. The solid residue was presumed to bestyrene homopolymer and to have about the same molecular weight assegments of polystyrene grafted onto the ethylene polymer backbone.

Percent styrene in the solid polymer product was determined by infraredspectroscopy as herein described and found to be 25.7 percent by weight.The solid residue was analyzed by gel permeation chromatography andfound to have a number average molecular weight (Mn) of 7082, a weightaverage molecular weight (Mw) of 9383 and a ratio of Mw/Mn of 1.32.

If one makes two assumptions, the number of side chains, or graftsegments, can readily be estimated. One assumption is that there is arandom distribution of polymer side chains each of which has the samemolecular weight. The other assumption is that the polymer side chainshave the same molecular weights as the polystyrene in the solid residue.Based upon these assumptions, the molar ratio of polystyrene to theoriginal EPDM polymer was calculated to be 4.97. In other words, therewere about 5 graft segments per olefin polymer chain.

EXAMPLE 15 Preparation of Grafted Polymer and Determination of GraftingEfficiency

A graft polymer was prepared by generally following the procedure ofExample 14 with different amounts of the same components as used inExample 14. The differences are set forth in succeeding paragraphs asappropriate.

Initially 14,006 milliliters of cyclohexane solvent and 280 grams of thesame EPDM terpolymer as used in Example 14 were added to the Five GallonReactor to prepare a polymer solution. Metallation reagents were addedas follows: (a) 10.3 milliliters of TMEDA; (b) 227.3 milliliters of a1.2 Molar solution of potassium-tert-amyloxide in cyclohexane; and (c)26.2 milliliters of a 2.6 Molar solution of n-butyllithium in hexane.The actual temperature of the reactor contents after metallation reagentaddition was 44° Centigrade.

Fifty minutes after addition of the metallating reagents, the reactorset point temperature was reduced to 30° Centigrade. Ten minutes laterthe actual temperature of reactor contents was 35° Centigrade. Aftersampling 200 milliliters of the reactor contents for analysis viasilicon-tagging, 248 grams of tetrahydrofuran were added gravimetricallyover a period of about five minutes. Fifteen minutes later, 150.8 gramsof styrene monomer were added gravimetrically over a period of threeminutes. The highest temperature measured after styrene addition was 35°Centigrade. The recovery vessel contained three gallons of n-propylalcohol rather than two gallons as in Example 14.

Percent styrene in the solid polymer product was 34.5 percent by weight.The solid residue was found to have a number average molecule weight(Mn) of 6590, a weight average molecular weight (Mn) of 9656 and a ratioof Mw/Mn of 1.47. The molar ratio was calculated to be 7.97. The numberof graft segments per olefin polymer chain was about eight.

The data presented in Examples 14 and 15 amply illustrate that graftcopolymers prepared in accordance with the present invention have atleast two pendant styrene polymer chains per ethylene polymer backbone.The pendant chains have a number average molecular weight sufficient toprovide the graft polymer with thermoplastic elastomer properties. Thedata also illustrate the marked effectiveness of the metallatingcomposition of the present invention. Similar results are obtained withother metallating reagents, ethylene polymers and monomers, all of whichare disclosed herein.

EXAMPLE 16 Preparation of Graft Polymer Using Diphenyl Ethylene as aNucleophilicity Moderator

Four hundred milliliters of cyclohexane and 12.2 grams of anethylene-propylene-diene terpolymer (hereinafter "EPDM") were added tothe 600 Milliliter Reactor and stirred to form a homogeneous mixture.Metallating reagents, 0.38 grams (0.25 milliliters) oftetramethylethylenediamine (TMEDA), 0.41 grams (2.71 milliliters) of 1.2Molar potassium-tert-amylate in cyclohexane and 0.21 grams (1.3milliliters) of 2.5 Molar n-butyllithium in hexanes were added to themixture in the order and amounts stated to form a reaction mixture. Thereaction mixture was heated to, and maintained at, a temperature of 30°Centigrade for a period of ninety minutes.

After about five minutes of heating, the reaction mixture began to turnred. Further heating darkened the color to deep red. In addition, thereaction mixture thickened to a point where it took on a gel-likeconsistency and began to climb up the stirring shaft after aboutthirty-five minutes of heating.

After the ninety minute period, heating was stopped and 80 milliliters(ml) of tetrahydrofuran (THF) was added to the reaction mixture to breakup the gel-like consistency. Immediately following addition of the THF,0.53 gram (0.52 ml) of diphenylethylene (DPE) was added to the dilutedreaction mixture. The diluted admixture was allowed to react for fiveminutes to form a modified reaction mixture.

A mixture of 12.2 grams (12.98 milliliters) of methylmethacrylate (MMA)monomer and 11.52 grams (12.98 milliliters) of THF was added to themodified reaction mixture and allowed to react. As polymerization of theMMA proceeded, the color of the reactor contents changed from dark redto yellow-brown. The polymerizing mixture began to gel as the colorchanged.

About 30 minutes after adding the mixture of MMA and THF to the modifiedreaction mixture, polymerization of MMA was terminated by adding 0.18grams (0.17 milliliters) of acetic acid to the polymerizing mixture.

Sixty-four grams (80 milliliters) of n-propanol were added to theterminated reaction mixture. The contents of the reactor vessel werethen heated to a temperature of 60° Centigrade for 15 minutes. Heatingwas then stopped. The contents of the reactor vessel were filtered whilehot through a 200 mesh (75 micrometer) wire screen. The filtrate wascollected in a recovery vessel.

The vessel was then covered and the contents were allowed to stand forsixteen hours. The contents settled into a gel layer and a liquid layer.After decanting the liquid layer from the gel layer, 400 milliliters ofdeionized water were added to the gel layer. The added water caused thegel layer to change to a layer of snow white, tacky material. Most ofthe water was then removed from the material by decanting.

The partially dry polymer was then immersed in an equal volume (400 mls)of (hot) acetone and heated to a temperature of 56° Centigrade for aperiod of ten minutes. Methylmethacrylate homopolymer, soluble in hotacetone, was thus removed from the tacky material. After decanting theacetone-homopolymer mixture from the tacky material, the remaining solidwas dried in a vacuum oven at a set temperature of 80° Centigrade for aperiod of about three hours.

After drying, the solid was analyzed for MMA content as detailed herein.The solid had an MMA content of 35 percent by weight of solid.

COMPARATIVE EXAMPLE W Preparation of Graft Polymer using α-MethylStyrene (α-MS) as a Nucleophilicity Moderator

The procedure of Example 16 was repeated except that 0.35 grams of α-MSwas used in place of the DPE. The resulting solid had an MMA content of33 percent by weight of solid.

COMPARATIVE EXAMPLE X Preparation of Graft Polymer Without aNucleophilicity Moderator

The procedure of Example 16 was duplicated except for the omission ofDPE and α-MS. The resulting solid had an MMA content of less than 8percent by weight of solid.

A review of Example 16 and Comparative Examples W & X illustrates twopoints. First, a much greater degree of grafting is obtained when anucleophilicity moderator is used. Second, α-methylstyrene is aseffective as diphenylethylene in terms of enhancing graftingeffectiveness. Similar results are expected with other polymers,monomers and the like, examples of which are disclosed herein.

What is claimed is:
 1. A process for preparing a thermoplastic graftpolymer having an ethylene polymer backbone and a plurality of sidechains which comprises:(a) providing a metallated ethylene polymer; (b)contacting the metallated ethylene polymer with a modifying compoundselected from the group consisting of alpha-methylstyrene,alpha-ethylstyrene, alpha-propylstyrene and alpha-isopropylstyrene underconditions sufficient to form a modified polymer wherein at least onemoiety of the modifying compound is attached to the ethylene polymerbackbone; and (c) contacting the modified polymer with at least oneanionically polymerizable monomer selected from the group consisting ofvinyl aromatic compounds, vinyl unsaturated amides, acrylonitrile,methacrylonitrile, organic isocyanates, organic diisocyanates, loweralkyl acrylates, lower alkyl methacrylate, lower olefins, vinyl estersof carboxylic acids, vinyl lower alkyl ethers, vinyl pyridines and vinylpyrolidones under reactive conditions sufficient to form the graftpolymer.
 2. The process of claim 1 wherein the modifying compound isalpha-methylstyrene.
 3. The process of claim 1 further comprisingdiluting the metallated ethylene polymer with a viscosity-reducingamount of a polar solvent prior to contacting the metallated polymerwith the modifying compound.
 4. The process of claim 3 wherein the polarsolvent is selected from the group consisting of dimethyl ether, diethylether, tetrahydrofuran, 2,5-dimethyl tetrahydrofuran, ethyl methylether, ethylene glycol dimethyl ether and diethylene glycol dimethylether.
 5. The process of claim 1 further comprising diluting themodified polymer with a viscosity-reducing amount of a polar solventprior to step (c).
 6. The process of claim 5 wherein the polar solventis selected from the group consisting of dimethyl ether, diethyl ether,tetrahydrofuran, 2,5-dimethyl tetrahydrofuran, ethyl methyl ether,ethylene glycol dimethyl ether and diethylene glycol dimethyl ether. 7.The process of claim 1 wherein the anionically polymerizable monomer isselected from the group consisting of vinyl aromatic compounds and alkylesters of alpha, beta-ethylenically unsaturated carboxylic acids.
 8. Theprocess of claim 1 wherein the anionically polymerizable monomer isselected from the group consisting of alkyl esters of acrylic acid andalkyl esters of methacrylic acid.
 9. The process of claim 1 wherein theanionically polymerizable monomer is methyl methacrylate, butylmethacrylate or tert-butyl methacrylate.
 10. The process of claim 1wherein step (c) is conducted at a temperature of greater than about-10° Centigrade.
 11. The process of claim 1 wherein step (c) isconducted at a temperature of from about 30° to about 50° Centigrade.12. The process of claim 1 wherein the ethylene polymer is aninterpolymer having polymerized therein, based upon interpolymer weight,from about 15 to about 99.5 percent ethylene, from about 0 to about 85percent 1-olefin and from about 0.5 to about 10 percent nonconjugateddiene.
 13. The process of claim 8 wherein the 1-olefin has from aboutthree to about twenty carbon atoms.
 14. The process of claim 8 whereinthe nonconjugated diene is selected from the group consisting of openchain, separated, nonconjugated dienes having from five to about twentycarbon atoms, cyclic nonconjugated dienes having from five to abouttwenty carbon atoms, and bicyclic nonconjugated dienes having from tento about thirty carbon atoms.
 15. The process of claim 1 wherein themetallated ethylene polymer is prepared by a process comprising:(a)providing an admixture of an ethylene interpolymer, said interpolymerhaving polymerized therein ethylene, a nonconjugated diene and at leastone 1-olefin having three or more carbon atoms, and a saturated nonpolarhydrocarbon solvent; (b) forming an intermixture of the admixture ofactivating amounts of a tertiary diamine and a potassium alkoxide; and(c) contacting the intermixture with an amount of at least one lithiumalkyl compound under conditions sufficient to provide a degree ofmetallation greater than the degree of metallation attained with (1) thepotassium alkoxide and the lithium alkyl compound, or (2) the tertiaryamine and the lithium alkyl compound, or by adding the degrees ofmetallation attained with (1) and (2).